1. Field of the Invention
The present invention relates to a prosthetic device for ligament reconstruction, and more particularly, to a fabric prosthetic device used for reconstruction of ligament tissue.
2. Description of the Related Art
Every year, hundreds of thousands of people sprain, tear, or rupture ligaments and tendons of the knee, elbow, hand, shoulder, wrist and jaw. One such ligament is the anterior cruciate ligament (ACL) of the knee. More than 200,000 people in the U.S. alone, tear or rupture their ACL each year. The ACL serves as a primary stabilizer of anterior tibial translation and as a secondary stabilizer of valgus-varus knee angulation, and is often susceptible to rupture or tear resulting from a flexion-rotation-valgus force associated with sports injuries and traffic accidents. Ruptures or tears often result in: severe limitations in mobility; pain and discomfort; and an inability to participate in sports and exercise. Failures of the ACL are classified in three categories: (1) ligamentous, in which ligament fibers pull apart due to tensile stress; (2) failure at the bone-ligament interface without bone fracture; and (3) failure at the bone-ligament interface with bone fracture at the attachment site of bone and ligament. Ligamentous failure is the most common type of ACL failure.
It is widely known that the ACL has poor healing capabilities. Total surgical replacement and reconstruction are required when the ACL suffers a significant tear or rupture. The most common practice is to reconstruct a torn ACL by substituting the torn ligament with the patient's own tissue, also known as an autograft. The middle third of the patellar tendon or the hamstring tendons are commonly used as autografts. Other options for substitute ligaments include donor tissues from a cadaver, also known as allografts, as well as synthetic grafts.
Conventionally, the techniques for reconstructing the ACL involve drilling tibial and femoral tunnels and pulling the autograft, allograft, or artificial ligament through the tunnels. The substitute ligament is then anchored to bone by a mechanical fixation device. Anchors may include the suspensory fixation, staples, as well as interference screws and cross pins. Often, the graft is folded in half to create a double bundle to more closely mimic the native human ACL. The size of the drilled bone tunnels depends on the size of the graft, which in turn depends on the strength of the graft material.
Although the use of autografts is common, the technique is disadvantageously accompanied by morbidity at the second surgery site from which the autograft is taken. For example, stress fracture of the patellar or weakness in the quadriceps muscle may occur, and a long rehabilitation period may be required. Furthermore, harvesting and preparation of autogeneous tissue prolong surgery time and cause additional trauma to the patient.
In-growth in the bone tunnels and about the device improves the device's strength and functionality over time. In addition, if sufficient in-growth does not occur, conventional devices may not be able to maintain proper flexibility, integrity, or tension in the long term.
In order to restore the stability of the knee with a replacement ligament, correct tensioning of the graft must also be established and maintained. A common mode of failure for conventional devices occurs when the devices loosen due to bone erosion and degradation around the implant site. In such cases, sufficient in-growth can fail to occur around the device within the bone tunnels. This then results in a slackening of the ligament and an eventual return to a dysfunctional knee.
Another disadvantage with conventional devices includes the release of debris from a failed ligament resulting in chronic inflammation of the joint. A further disadvantage includes osteolysis of bone, in and around the area of ligament attachment. Moreover, device abrasion may occur at the bone tunnel apertures.